Abstract
Mitogen-activated protein kinase (MAPK) cascades are rapidly activated upon plant recognition of invading pathogens. Here, we describe the use of virus-induced gene silencing (VIGS) to study the role of candidate plant MAP kinase kinase kinase (MAPKKK) homologs of human MEKK1 in pathogen-resistance pathways. We demonstrate that silencing expression of a tobacco MAPKKK, Nicotiana Protein Kinase 1 (NPK1), interferes with the function of the disease-resistance genes N, Bs2, and Rx, but does not affect Pto- and Cf4-mediated resistance. Further, NPK1-silenced plants also exhibit reduced cell size, defective cytokinesis, and an overall dwarf phenotype. Our results provide evidence that NPK1 functions in the regulation of N-, Bs2-, and Rx-mediated resistance responses and may play a role in one or more MAPK cascades, regulating multiple cellular processes.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Cell Size / genetics
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Gene Expression Regulation, Plant / physiology*
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Gene Silencing / physiology*
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Genetic Vectors / genetics
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Immune System / enzymology*
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Immunity, Innate / immunology*
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MAP Kinase Kinase Kinase 1*
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MAP Kinase Kinase Kinases / genetics
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MAP Kinase Kinase Kinases / immunology*
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MAP Kinase Kinase Kinases / metabolism
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Nicotiana / enzymology*
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Nicotiana / growth & development
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Nicotiana / immunology
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Plant Diseases*
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Plant Proteins / genetics
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Plant Proteins / immunology*
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Plant Proteins / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / immunology*
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Protein Serine-Threonine Kinases / metabolism
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RNA, Messenger / metabolism
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Sequence Homology, Nucleic Acid
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Signal Transduction / genetics
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Tobacco Mosaic Virus / genetics
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Tobacco Mosaic Virus / immunology
Substances
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BS2 protein, Capsicum chacoense
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Plant Proteins
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RNA, Messenger
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Protein Serine-Threonine Kinases
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MAP Kinase Kinase Kinase 1
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MAP Kinase Kinase Kinases
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MAP3K1 protein, human
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NPK1 protein, Nicotiana tabacum